Vapor chamber structure and method of manufacturing same

ABSTRACT

A vapor chamber structure and a method of manufacturing thereof are disclosed. The vapor chamber structure includes a main body formed of a metal plate and a ceramic plate. The metal plate and the ceramic plate are closed each other to define a chamber therebetween; the chamber is internally provided with a wick structure, a support structure, and a working fluid. The metal plate and the ceramic plate are connected each other via welding or a direct bonding copper process, and the support structure is connected to between the metal plate and the ceramic plate via welding or the direct bonding copper process. By contacting the ceramic plate of the vapor chamber with a heat source packaged in a ceramic material to transfer heat, the problem of crack at an interface between the vapor chamber and the heat source due to thermal fatigue can be overcome.

This application claims the priority benefit of Taiwan patent application number 100130954 filed on Aug. 29, 2011.

FIELD OF THE INVENTION

The present invention relates to a vapor chamber structure, and more particularly to a vapor chamber structure formed of a metal plate and a ceramic plate to overcome the problem of crack at an interface between a vapor chamber and a heat source due to thermal fatigue. The present invention also relates to a method of manufacturing the above described vapor chamber structure.

BACKGROUND OF THE INVENTION

The progress in semiconductor technology enables various integrated circuits (ICs) to have a gradually reduced volume. For the purpose of processing more data, the number of computing elements provided on the presently available ICs is several times higher than that on the conventional ICs of the same volume. When the number of computing elements on the ICs increases, the heat generated by the computing elements during the operation thereof also increases. For example, the heat generated by a central processing unit (CPU) at full-load condition is high enough to burn out the whole CPU. Thus, it is always an important issue to properly provide a heat dissipation device for ICs.

The CPU and other chips are heat sources in the electronic device. When the electronic device operates, these heat sources will generate heat. The CPU and other chips are mainly encapsulated with a ceramic material. The ceramic material has a low thermal expansion coefficient close to that of chips used in general electronic devices and is electrically non-conductive, and is therefore widely employed as packaging material and semiconductor material.

On the other hand, a heat dissipation device usually includes a heat dissipating structure made of an aluminum material or a copper material, and is often used along with other heat dissipation elements, such as fans and heat pipes, in order to provide enhanced heat dissipation effect. However, in considering the reliability of the electronic device, the use of a heat dissipation structure with cooling fans and heat pipes would usually have adverse influence on the overall reliability of the electronic device.

Generally speaking, a heat dissipation device with simpler structural design would be better to the overall reliability of the electronic device. Thus, the heat transfer efficiency of the electronic device can be directly improved when the heat dissipation device used therewith uses a material having better heat transferring and radiating ability than copper.

In addition, heat stress is another potential factor having adverse influence on the reliability of the electronic device in contact with the heat dissipation device. The heat source, such as the chip in the CPU, has a relatively low thermal expansion coefficient. To pursue good product reliability, the electronic device manufacturers would usually use a ceramic material with low thermal expansion coefficient, such as aluminum nitride (AlN) or silicon carbide (SiC), to package the chip.

Further, in the application field of light-emitting diode (LED) heat dissipation, for example, aluminum and copper materials forming the heat dissipation device have thermal expansion coefficients much higher than that of an LED sapphire chip and the ceramic packaging material thereof. In a high-brightness LED, an interface between the aluminum or copper material of the heat dissipation device and the ceramic packaging material of the LED sapphire chip tends to crack due to thermal fatigue caused by the difference in the thermal expansion coefficients thereof when the LED has been used over a long period of time. The interface crack in turn causes a rising thermal resistance at the interface. For the high-brightness LED products, the rising thermal resistance at the heat dissipation interface would result in heat accumulation to cause burnout of the LED chip and bring permanent damage to the LED.

In brief, the difference between the thermal expansion coefficients of the ceramic packaging material of a heat source and the metal material of a heat dissipation device would cause crack at an interface between the heat source and the heat dissipation device due to thermal fatigue; and it is necessary to work out a way to solve the problem of such crack at the interface.

SUMMARY OF THE INVENTION

A primary object of the present invention is to provide a vapor chamber structure that overcomes the problem of crack at an interface between the vapor chamber and a heat source due to thermal fatigue.

Another object of the present invention is to provide a method of manufacturing a vapor chamber structure that can overcome the problem of crack at an interface between the vapor chamber and a heat source due to thermal fatigue.

To achieve the above and other objects, the vapor chamber structure according to the present invention includes a main body formed of a metal plate and a ceramic plate. The metal plate and the ceramic plate are correspondingly closed to each other to thereby together define a chamber therebetween. The chamber is internally provided with a wick structure, a support structure, and a working fluid. The wick structure is located on inner wall surfaces of the chamber, and the support structure is connected to between the metal plate and the ceramic plate.

The wick structure is selected from the group consisting of a sintered powder structure, a netlike structure, and a plurality of grooves. The ceramic plate is made of a material selected from the group consisting of silicon nitride (Si₃N₄), zirconium nitride (ZrO₂), and aluminum oxide (Al₂O₃). And, the support structure includes a plurality of copper posts.

The support structure is connected to the ceramic plate in a manner selected from the group consisting of soldering, brazing, diffusion bonding, ultrasonic welding, and direct bonding copper (DBC) process.

To achieve the above and other objects, the vapor chamber structure manufacturing method according to the present invention includes the following steps:

-   -   (a) providing a metal plate and a ceramic plate;     -   (b) providing a wick structure and a support structure on faces         of the metal plate and the ceramic plate that are to be faced         toward each other later; and     -   (c) correspondingly closing the metal plate and the ceramic         plate to each other to define a chamber therebetween, evacuating         the chamber, filling a working fluid into the chamber, and         sealing a joint between the closed metal plate and ceramic plate         to complete a vapor chamber.

According to the method of the present invention, the metal plate and the ceramic plate are connected to each other by way of soldering, brazing, diffusion bonding, ultrasonic welding, or direct bonding copper (DBC) process.

According to the present invention, a ceramic plate is applied in the vapor chamber structure to connect to a metal plate, and it is the ceramic plate of the vapor chamber that is in contact with a heat source packaged in a ceramic material. Since the ceramic plate of the vapor chamber structure and the ceramic packaging material of the heat source are close in their thermal expansion coefficients, it is able to avoid the problem of crack at an interface between the vapor chamber and the heat source due to thermal fatigue caused by different thermal expansion coefficients of the vapor chamber and the heat source.

BRIEF DESCRIPTION OF THE DRAWINGS

The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein

FIG. 1 a is an exploded perspective view of a vapor chamber structure according to a first embodiment of the present invention;

FIG. 1 b is an assembled view of FIG. 1 a;

FIG. 2 is a cross sectional view of the vapor chamber structure according to the first embodiment of the present invention;

FIG. 3 is a cross sectional view of a vapor chamber structure according to a second embodiment of the present invention;

FIG. 4 is a cross sectional view of a vapor chamber structure according to a third embodiment of the present invention; and

FIG. 5 is a flowchart showing the steps included in a method of manufacturing vapor chamber structure according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with some preferred embodiments thereof and with reference to the accompanying drawings. For the purpose of easy to understand, elements that are the same in the preferred embodiments are denoted by the same reference numerals.

Please refer to FIGS. 1 a and 1 b that are exploded and assembled perspective views, respectively, of a vapor chamber structure according to a first embodiment of the present invention; and to FIG. 2 that is a cross sectional of the vapor chamber structure of FIG. 1 b.

As shown, the vapor chamber structure in the first embodiment includes a main body 1. The main body 1 is formed of a metal plate 11 and a ceramic plate 12, which are correspondingly closed to each other to thereby together define a chamber 13 therebetween. The chamber 13 is internally provided with a wick structure 14 and a support structure 15. The wick structure 14 is located on inner walls of the chamber 13, and the support structure 15 is located between and connected to the metal plate 11 and the ceramic plate 12. A working fluid 16 is filled into the chamber 13.

In the illustrated first embodiment of the present invention, the wick structure 14 includes, but not limited to, a sintered powder structure.

The ceramic plate 12 can be made of silicon nitride (Si₃N₄), zirconium nitride (ZrO₂), or aluminum oxide (Al₂O₃).

The support structure 15 includes a plurality of copper posts that are connected to the ceramic plate 12 by way of soldering, brazing, diffusion bonding, ultrasonic welding, or direct bonding copper (DBC) process.

The metal plate 11 is made of a copper material, an aluminum material, a stainless steel material, or any other metal material with good heat radiating and thermal conducting properties.

Please refer to FIG. 3 that is a cross sectional view of a vapor chamber structure according to a second embodiment of the present invention. As shown, the second embodiment is generally structurally similar to the first embodiment, except that the wick structure 14 in the second embodiment includes but not limited to a netlike structure.

FIG. 4 is a cross sectional view of a vapor chamber structure according to a third embodiment of the present invention. As shown, the third embodiment is generally structurally similar to the first embodiment, except that the wick structure 14 in the third embodiment includes but not limited to a plurality of grooves.

FIG. 5 is a flowchart showing the steps included in a method of manufacturing vapor chamber structure according to an embodiment of the present invention. Please refer to FIG. 5 along with FIGS. 1 to 4. The vapor chamber structure manufacturing method according to the present invention includes the following steps S1, S2 and S3.

In the step S1, a metal plate and a ceramic plate are provided.

More specifically, a metal plate 11 and a ceramic plate 12 are provided. The metal plate 11 is made of a metal material selected from the group consisting of a copper material, an aluminum material, a stainless steel material, and any other metal material with good heat radiating and thermal conducting properties. The present invention is explained with the metal plate 11 being made of a copper material but not intended to be limited thereto. And, the ceramic plate 12 is made of a material selected from the group consisting of silicon nitride (Si₃N₄), zirconium nitride (ZrO₂), and aluminum oxide (Al₂O₃). The present invention is explained with the ceramic plate 12 being made of aluminum oxide (Al₂O₃) but not intended to be limited thereto.

In the step S2, a wick structure and a support structure are provided on faces of the metal plate and the ceramic plate that are to be faced toward each other later.

More specifically, the metal plate 11 and the ceramic plate 12 are provided on respective one face that are to be faced toward each other with a wick structure 14 and a support structure 15. The wick structure 14 can include a sintered powder structure, a netlike structure, or a plurality of grooves. In the case the wick structure 14 in the form of a sintered powder structure is desired, a type of powder can be sintered to thereby become molded on the metal plate 11 and the ceramic plate 12.

In the case the wick structure 14 in the form of a netlike structure is desired, the netlike structure can be connected to the ceramic plate 12 and the metal plate 11 by soldering, brazing, diffusion bonding, ultrasonic welding, or direct bonding copper (DBC) process.

Or, in the case the wick structure 14 in the form of a plurality of grooves is desired, the metal plate 11 and the ceramic plate 12 are subjected to a mechanical process, such as milling, planing, laser cutting or etching, to form a plurality of grooves thereon.

The support structure can include a plurality of copper posts, which can be first connected to either the ceramic plate 12 or the metal plate 11 by soldering, brazing, diffusion bonding, ultrasonic welding, or direct bonding copper (DBC) process.

In the step S3, the metal plate and the ceramic plate are correspondingly closed to each other to define a chamber therebetween, the chamber is evacuated, a working fluid is filled into the evacuated chamber, and a joint between the metal plate and the ceramic plate is sealed.

More specifically, the metal plate 11 and the ceramic plate 12 are correspondingly closed and fixedly connected to each other by soldering, brazing, diffusion bonding, ultrasonic welding, or direct bonding copper (DBC) process, so that a chamber is defined between the metal plate 11 and ceramic plate 12. The chamber is evacuated and then filled with a working fluid 16. Finally, a joint between the connected metal plate 11 and ceramic plate 12 is sealed to complete a vapor chamber.

The present invention is characterized in that the ceramic plate 12 is used as one of two sides of the vapor chamber for contacting with a heat source to transfer heat. That is, one of two metal sides of the conventional vapor chamber is replaced by the ceramic plate 12 in the present invention. Since the ceramic plate 12 has a thermal expansion coefficient close to that of the ceramic packaging material of the heat source in an electronic device, it is able to avoid the problem of crack at an interface between the vapor chamber and the heat source due to thermal fatigue caused by different thermal expansion coefficients of the vapor chamber and the heat source. With one of two sides of the vapor chamber being made of a ceramic material, the vapor chamber as a heat dissipation device can be applied to more different fields.

The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims. 

1. A vapor chamber structure, comprising a main body formed of a metal plate and a ceramic plate; the metal plate and the ceramic plate being correspondingly closed to each other to thereby together define a chamber therebetween; the chamber being internally provided with a wick structure, a support structure, and a working fluid; the wick structure being located on inner wall surfaces of the chamber; and the support structure being connected to between the metal plate and the ceramic plate.
 2. The vapor chamber structure as claimed in claim 1, wherein the wick structure is selected from the group consisting of a sintered powder structure, a netlike structure, and a plurality of grooves.
 3. The vapor chamber structure as claimed in claim 1, wherein the ceramic plate is made of a material selected from the group consisting of silicon nitride (Si₃N₄), zirconium nitride (ZrO₂), and aluminum oxide (Al₂O₃).
 4. The vapor chamber structure as claimed in claim 1, wherein the support structure is connected to the ceramic plate and the metal plate in a manner selected from the group consisting of soldering, brazing, diffusion bonding, ultrasonic welding, and direct bonding copper (DBC) process.
 5. The vapor chamber structure as claimed in claim 1, wherein the support structure includes a plurality of copper posts.
 6. The vapor chamber structure as claimed in claim 1, wherein the metal plate is made of a material selected from the group consisting of a copper material, an aluminum material, a stainless steel material, and any other metal material with good heat radiating and thermal conducting properties.
 7. A method of manufacturing vapor chamber, comprising the following steps: (a) providing a metal plate and a ceramic plate; (b) providing a wick structure and a support structure on faces of the metal plate and the ceramic plate that are to be faced toward each other later; and (c) correspondingly closing the metal plate and the ceramic plate to each other to define a chamber therebetween, evacuating the chamber, filling a working fluid into the chamber, and sealing a joint between the closed metal plate and ceramic plate to complete a vapor chamber.
 8. The vapor chamber manufacturing method as claimed in claim 7, wherein the wick structure is selected from the group consisting of a sintered powder structure, a netlike structure, and a plurality of grooves.
 9. The vapor chamber manufacturing method as claimed in claim 7, wherein the ceramic plate is made of a material selected from the group consisting of silicon nitride (Si₃N₄), zirconium nitride (ZrO₂), and aluminum oxide (Al₂O₃).
 10. The vapor chamber manufacturing method as claimed in claim 7, wherein the support structure is connected to the ceramic plate and the metal plate in a manner selected from the group consisting of soldering, brazing, diffusion bonding, ultrasonic welding, and direct bonding copper (DBC) process.
 11. The vapor chamber manufacturing method as claimed in claim 7, wherein the support structure includes a plurality of copper posts.
 12. The vapor chamber manufacturing method as claimed in claim 7, wherein, in the step (c), the correspondingly closed metal plate and ceramic plate are connected to each other in a manner selected from the group consisting of soldering, brazing, diffusion bonding, ultrasonic welding, and direct bonding copper (DBC) process. 